The present invention relates to coating compositions for flexible, sheet-like substrates, coated flexible, sheet-like substrates for articles of manufacture used in contact with human body surfaces, and a process for adding waxy compositions to flexible, sheet-like substrates. The present invention is particularly useful for coating compositions for flexible, sheet-like substrates, coated flexible, sheet-like substrates used in the manufacture of disposable absorbent articles, specifically suited for coated flexible, sheet-like substrates used in the manufacture of tampons.
There are several methods of delivering waxy compositions to their intended targets, including but not limited to oral, topical, and transdermal methods. Disposable absorbent articles can be used as vehicles for topical delivery to the vaginal canal, perineum, and related areas, as well as for treatment sites for the discharged fluids to come in contact with the waxy compositions, as they are captured by the product.
Duchane, U.S. Pat. No. 3,796,219 discloses a water-soluble, thermoplastic compound for hygienic and medical applications, such as for use as an insertion aid coating for tampons and as the matrix structure for suppositories. The coating is stable in temperatures up to 65° C., and it provides lubricity at temperatures below 65° C. when exposed to shear forces, as those present during insertion of the tampon. Duchane discloses the use of two olefinic diols, polyethylene glycol and propylene glycol in combination with hydroxypropyl cellulose (HPC) having a molecular weight of approximately 75,000. The resulting composition is stable at temperatures up to 65° C. Von Bittera et al., U.S. Pat. No. 4,582,717, discloses a process for producing vaginal tampons containing a pharmaceutical active compound. The process involves preparing a material containing the active compound and additional formulation auxiliaries, heating the material to a temperature in excess of 40° C., cooling the melt to 40° C., and then injecting the cooled material into pre-warmed tampons. One of the formulation auxiliaries disclosed in von Bittera is polyethylene glycol (PEG) having moderate molecular weight.
Yang, U.S. Pat. No. 6,316,019 discloses a process for making a tampon including the application to a substrate of a solution containing a pharmaceutically active compound. The solution is liquid at a temperature of less than about 35° C., and it is applied to the disposable absorbent article at a temperature of less than 40° C.
A common theme of the art shown above is the attempt to provide a coating that is stable above room temperature, but is liquid at or near body temperature (37° C.). This provides significant challenges to handling the components in high speed manufacturing processes without loss by transfer to the processing equipment.
Brown-Skrobot, U.S. Pat. No. 5,679,369, discloses additives to tampons to inhibit the production of toxic shock syndrome toxin-1. The additives generally are not liquid at or near room temperature, and therefore, they require a carrier material, such as isopropyl alcohol. This technology represents an important advance in the art, but the disclosed process of applying the additive may require a recovery process to capture the volatile alcohol.
While this is an advance in the art, the ability to add substantial amounts of the pharmaceutically active compound to the substrate to form a robust and flexible coated material is limited.
Therefore, what is needed are coating compositions and coated substrates that form a robust and flexible coated material and that provide desired properties to articles of manufacture used in contact with human body surfaces, such as a body-side liner or cover of an absorbent article, such as a tampon. Further, what is needed are coating compositions and coated substrates that are processable in a commercially efficient manner, that provide satisfactory fluid transport into the absorbent article, and that aid in removal of the tampon from an overwrapper or applicator prior to and/or during use.